The OM3-1.1 hybridoma cell line (ATCC HB-134™) was seeded in growth medium containing HAT. The population doubling time after two days of growth was ≤ 24 hours, indicating good growth, as expected for HAT resistant hybridoma cells. The P3/NSI/1-Ag4-1 (NS-1) plasmacytoma cell line (ATCC TIB-18™) was seeded in growth medium containing HAT. The cell concentration after 2 days of growth showed ≤ 20% change, indicating that the cells were dying in the presence of HAT, as expected for HAT-sensitive plasmacytoma cells.